Electronic timing apparatus



April 5, 1960 K, R, WENDT ETAL 2,931,217

ELECTRONIC TIMING APPARATUS Filed Oct. 27, 1955 5 Sheets-Sheet l v E l I ,f4 "mm M4 I $2) ops/v I6,

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10650 GATE I ,I e, I I I PHASE 4. /lV VERTE'R I I e4 I e1 @Mmmm/mp ww M 6 :cu/RATE I ez JI-II-II- ILILILILILJLILIL cya/ $12036 f5-.046' 62.0.53

' WA H5000? :ferai/day 0 6'50 0 720 0 765 I e@ M MLIJULMLIL t Fig/.4

April s, 1960 K R, WENDT m1 2,931,217

ELECTRONIC TIMING APPARATUS Filed Oct. 27, 1955 3 Sheets-Sheet 2 INVENTORSz Kar/ R Wend qnd( W/V//am K. 57m/res,

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` ATTORNEYj April 5, 1960 K. R. WENDT EVAL ELECTRONIC TIMING APPARATUS Filed Oct. 27, 1955 3 Sheets-Sheet 3 j, 400 MILL/.SEco/vas FQM PULs me .34

IN VENTORSI i 2,931,211 ELECTRONIC. riunisceanni?Albums:V g

yseriesM ofeventsswhichiit" `is desiredtobririg into agree'i tirentwithsueirtimescale.`

i More" specically, `the invention "is concerned with -tirh-N ship between` airv ,accurately `pr'oiiuced'- time sca-1e' and va i'rigfapparatus* for measuring and displaying` the' timing Y characteristics of a watch, clock or the like, in'ls'u'cli a Wayfas" to permit the operatorl to obta'inara'pid and'cornple'tean'alysis of rate erro'rsandotli'er anomalieslinthe perationV of the timepiece, usually with a viewtotheir correction.' The invention" willi be describedin connection With' thisV preferred' applicationfbecause su'cl asp'ei c i'description willrender the principles of' the invert# tion more readily understood. lliowev'er, it w'ilhbeapL 'aparent to those skilled" in the arf; rh'atf diese' same prim cipies 'maybe appliedto'otlier timiiigfproblems, especiali 1y' tho'se .involving thet timing 'ofV a" repeated seriesk(if events Whose* occurrence" may-be sensed byelec'tricfal means; 'Y Y' It is recognied that'elctronic principles; such as't'he uselof accurate oscillators'andthelike, have been'pro'- posed many' times for the accomplishment of' timing fiinctions, and evenspecically'for the determinaiionand display of errors in Watches and the like. However; all such proposals of which we are aware havefconcerne'd themselves with the problem of the generation of a` freqency of high accuracy, so that'when it'isV compared with the frequency'of watch beats, for example, any'dii# .ference can be detected ina reasonably short interval.

The' general approach has been to"over`coriie the problem v of the sensing of smallV errors by the'luse of increased precision in lthe standard time scale produced electrical- The importance of this phase of the problem is o f course well recognized, and maybe realized more-fully considering that the detection of an error in a timel v,

`piece as small as afew seconds a day, by the classica-l t .Y

method of observing the indicated time against a standL a'r'd `tlircmometer, requires at lea'stjV several hours .of Aob servation time in order that the extremely small inst'arii` tneous er'rormayV accumulate to the'poirit vvhereit can be observed and corrected]v This'f observation time is ofl Vcourse multiplied v vhenit is necessary lor desired `toob= t'ain i''n indication of the errors in the timepiece Ain 'eachfV f several positions "of orientation thereof, asrequired,

:for example, in the testing'of watches for standardceri u tfiiicates. Evenfor the relativelyle'ss precise adjustment ofwatches fory commercial purposes, both the classical, method of chronometric comparison, fand the known require considerable observationtimes.,

4The presentinvention overcomes these objectionsV to i the prior methods not ,simply` byin'creasing' the precision ofthe generated comparison;freiuencbut b y further improvements which give adir-ect and alfrriostrimmediate en efite direction'erfserrse 5f-trie'timepiece"er'-r 'chronous timei'iiece.`

Anothery object of the u @,ers incorporatedLin thelpdisplay which vvill"alvvaysl he electronic Systems utilizing precision frequency sources', i,

une

,display of the comparative information (timepiece rate against` standard timescale) inl such aiway: as to yield additional informationv ofvalue to theA technician who Wish'es to adjust the timepiece' to reduce; thisdifference tofaim-in`imum' value. Inconventional timepieces, alternate beats are produced at the opposite ends ofthe swing: o'f the,escapeinemV pallet. Referring to these a1- trratingbeats asticks and tocks, it is' apparent that even `in an accurately adjusted timepiece, imperfectio'risorfmaladjustments-of' tliel pallet, anchor orother parts may result in asymmetryfjthus, the time` interval between a= tic'k andiatook-l rha'y be different yfrom that between af tock and alticki` Thisl isi al condition which should be corrected if the timepiece is to function-de- Vpendablyover long periodanannderfditferent conditiens ofuseororientatiori: t l

An additional object of the` invention is to provide' a system oftheabeve general fypeiinivvhi'ehfthe nn'at vinformation displayed to the observer isi limited to'that which is directly useful in the desired determinations. That is, since the period'oc'c'upied by the actual generationof av tick or a tockis a rather smalle part ofthetotall time between-these impulses, sig-nificant information `can be derived electricallyV only fory thisy fractional 'period. The invention displays only the l significant portion of the information, and -this permits al scale to be used which is muchmore indicative of the-condition. of the timepiece than' if the entiretick-took cycle were displayed to the observer. i

StillY anotherimportant objectk of the` inventionis to provide for adjusting -the sweeprepetition rate-to agree withV -the rate of aV timepiece- In particular, meansI are proyided such that'the error inthereadingofa rate diai controlling ,thev svveep rate-,decreases for watches whose errors approach zero.: Thus, theV calibration-establishing means may beirelatively simple because errorsof kany magnitude intlieacalibration will only arise in connection-with the testing'of al timepiece having a rather gross clirorrometric'error; iAsithe timepiece isl adjustednearer `andinearer-1totan idealfcondition, the error inherent in Ytle rate-control or'di'al reading is automatically reduced until `such Aerror vanishes, the' case of a. perfectly' isoinvention i isi to provide .'f'rl markstanding still andalWaysSeparated from oneanother'by ardistance corresponding to" a precise' time inte'rvail 'Fliese'markers serve; to measure portions (andtheivhole) of the watchv trace-to aidin judging alignment between thel tick and" to'ck, 'and yas Aan"l additional measure" of slow drifts in rate.

Arfurther object ofthe invention isftofprvid'e apparats Y of the'above' type which is adapted for use With timepieces` (orl other time-series devices) havingdistin'ct .re'petiL tion rates oirbeats per second. In the casievo'ffwatches, forvexampie, lescape'rrient trainsA utilizing,v 5f, 51/2` and' 6 beatsfpersecondarecdnnnon. While it Wouldptiepsisible. te; previqererv inesenifrerenr types; by y,utilizingV aL corresponding number of precision frequency generators,

or by a single generator and a plurality of frequency divider systems, any calibration marks utilized could be correct for only one of the types of timepieces. The present invention provides novelY means for'deriving information as to timepieces having different number of beats per second, without disturbing the precision of the calibration markers, andof such kindthat the apparatus may be properly adjusted for the desired beat by manipulation of a single selector control.`

The above and other objects and advantages of the invention will best be understood by referring now to the following detailed specification of a preferred embodiment thereof, given by way of example, and taken in connection with the appended drawings, in which:

Fig. 1v is a block diagram of a complete timing apparatus and system of preferred form.

Fig. 2 is also a block diagram giving more detail as to a novel portion of the Fig. 1 arrangement.

Fig. 3 is a graphical representation of a series of Waves or pulse trains which will aid in understanding the invenf tion.

Fig. 4 is a tabulation giving the valuesy of certain parameters of the system for use with watches having different numbers of beats per second.

Fig. 5 is a schematic wiring diagram of a complete embodiment of the invention.

Fig. 6 is a further graphical representation ofthe sweep separation and scan waves showing their timing relationships. v Fig. 7 is a block diagram of a modified form of narrowrange frequency adjusting system suitable for use with the invention.

,Fig 8 is a schematic of circuit elements the Fig. 7 modification.

applicable to General description day. Moreover, it would not be desirable to adjust the frequency of the oscillator 10 during the use of the instrument, because to do-so would involve a loss of its calibration standard. y

^ For a reason which will appear, the natural frequency of oscillator 10 is chosen at 99 kilocycles per second, which is a frequency readily obtainable from such equipment in simple form. ,In order to provide a suitable range of variation inthe effective output frequency, apparatus designated generally by reference numeral 14 is provided, the same permitting the selective addition or subtraction of pulses to the train of pulses derived from the oscillator 10. In this connection, it may be stated that if the output of oscillator 10 is, as conventional for such devices, a sinusoidal voltage wave, the equipment 14 first converts this output wave to a series of narrow pulses of xed polarity; for instance, a single narrow positive-going pulse for each vpositive half cycleof the sine wave produced by oscillator 10. It is these pulses which control the timing characteristics of the remaining circuitry, and device 14 enables additional pulses to be inserted periodically in the train, to raise the apparent or effective pulse frequency at the output of the device 14; it also permits the selective elimination of certain of the pulses derived from oscillator 10, to permit a reduction in the apparent output frequency.

The pulses of master oscillator frequency, or as modified in frequency as just described, are then passed to a The timing system of the invention utilizes as the source the magnetostrictive type, or may be any other electric generator or standard frequency source capable'of the necessary -precisionin frequency. Such an oscillator necessarily produces output frequencies very much higher than can be used for directcomparison with watches having beat rates of only a few per second, and it is common ir. the timing art to provide frequency division means` to derive from the oscillator 10 a much lower frequency, but one of precision comparable to the precision of the master oscillator. The present invention does not provide for the immediate frequency division of the output of oscillator 10, and instead accomplishes this division procedure after the effective frequency derived from the oscillator has been altered in aspecial way to be described below. Numeral 12 designates a Vernier. connected to or forming a part of oscillator 10, bywhich its natural frequency of loscillation may be adjusted a minor amount to conform exactly to any available` primarystandard of frequency. Thus, the vernier may be adjusted to 'minimize the error between the frequency output of oscillator 10 as compared against a standard frequency broadcast, standard time signals, or a laboratory source of adequaterprecision. However, the degree to which the frequencyof an electronic source such yas oscillator 10 can be vadjusted is wholly inadequate to v accomplish the frequency changes necessary to permit direct comparison with timepieces having normal rate errors as encountered in commercial practice. For example, a crystal-control oscillator can be varied in fr equency by a few cycles per second by adjusting the capacitance in series withY or in shunt to the crystal itself, and' by other ways familiar to those experienced withusuch oscillators, but-such deviationsare notsufliciyent tomatch errors in watch` rates even as low as several seconds per frequency dividing circuit 16 which effects a division of the frequency by a factor of 300 in the embodiment here being described. In the case in which no pulses are added or subtracted by the apparatus 14, the input to frequency divider 16 will consist of 99,000 pulses per second, and its output will therefore be 330 pulses per second. A portion of this output passes then into a secand frequency divider 18 which is adjustable to effect division by a vfurther factor which may be either 66, 60 or 55, to provide an output of 5, 51A or 6 pulses per second as indicated. These frequencies as stated are also for the normal or unmodified frequency of precisely 99 kilocycles from oscillator 10, and of course will be slightly different if pulses are added or subtracted due to the operation of device 14. From divider 18 the pulses just described pass to a sweep pulser 20 whose function is to produce a 40 millisecond sweep pulse for each of the input pulses; e.'g., 5,15% or 6 times per second. This 40 millisecond sweep pulse is applied to the sweep generator 22 to cause the latterY to supply a linearly rising voltage wave lto the horizontal deliecting electrodes 26 of the cathode ray tube 24, for the duration of each 40 millisecond pulse.

The reason for utilizing a sweep pulse having a width of only 40 milliseconds for each sweep cycle is that it is desired to display only the information derived from the tick and tock sensing means in the region of occurrence of these beats. Since at 5 or 6 beats per second the total beat interval is of the order of 200 milliseconds, the use of the narrower 40 millisecond pulses to control sweep oscillator 22 produces sweep display only during the significant intervals, and permits a larger horizontal scale of display to be1utilized. y

From frequency divider 16, another portion of its output (nominal 330 pulses per second) is applied to the `series of dark dots spaced as determined by the pulse frequency output of divider 16. Since both the sweep oscillator 22and the intensity control electrode 28 are governed by the outputvof divider 16, both of these will partake of theminor frequency variations introduced by ,the pulse adder and subtractor 14; howeventhese minor,`

variations are accomplished during the period preceding pulses per' secondat itsoutput.

14 isscnergizedV for alV selected asquare p,uls`eof'variahle time duration. i Y variable width pulser 34 is then applied'to device 14 to display. 'Ihatisg vthe variations introduced by the pulse addon andV subtractorylt a'll take.- placerland? are completebeforethegiirst dot shows in thefdeection. Hence, during; the'. resti` of theA sweep, multipleof the-crystal,l and therefore accurately 3,0303 milliseconds apart; Actually,. .when` the rate dial is rotated, the dots all move with respect to the start of scan. The extrememotioriis one Whole dot, since yi150 pulses at 10.1 microseconds happens to be exactly $0303 milliseconds. This will be true regardless of tliesetting of selective divider lfto produce 5, 51/2 or 6 The reasonfor selecting 1`50`as' thcnumber of pulses which may beaddelo'r'sub'- tractedis that this number provides a useful adjustment range from about 4% seconds per vdayto about'650 seconds' .per day, fast or slow, as` willbe explained belou under thieheadingl Frequency Varying System. This is"becausethe frequency of`*330 pulses'per' second is a commonmultiple of v5,5 1/2 `and 6, and isan integral submultple .ofthe master frequency of'9'9'lilo'cycles; The reason for thechoice of the fundamental Yfrequency of 991 kc. is now apparent,- since it permits aV stationary trace" p,attern,.and` stationary calibration dots, forall values of the .selective frequency division.

Aportion of the pulse output ofvpulser 20 is alsov ap# pliedSas indicatedpat connection 30, to the intensity' con troll electrode.Y 28': Its amplitude and polarity are so chosen as to suppress the bright trace eX'cept during the 40'millisecond'sweep period. This feature prevents blurringJof the trace at'either of its ends which would other.'- wise'result from the rather lengthy Vexposure of the screen phosphor at these points during. the interval between horizontal sweeps. K

Ih` order to control the number of pulseswhich' are addedtto orsubtractedfrom the master series produced lay-oscillator 10, the pulse adding and subtracting device portion-ofeach complete sweep, cycle. Conveniently, this timed energiztion is obtained-by deriving from the sweep pulser 20! an output over connection 32 in the form of one pulse forfeach sweep cycle. This outputlis appliedto thelvariable width pulser'34, whichis triggered by the leading edge ofthe 40' millisecond pulse from 20,` and provides at its output The output of regulteLhow many pulses are added to or removed from theloriginalseries derived from oscillator `to establish the awrage pulse repetition frequency'emittedby the device 1'4 to the divider 16.H The details" of this`part 'o'f the .operation willbe describedniore fully bolo-w'.

Iheinformation derived from a timepiece being tested, designated in Fig. 1 byV numeral 36, maybe obtained from. any known or convenient microphone, vibration pickup or other transducer designated 38. The .electricall output ofl this transducer is transmitted..l through an addition circuit Il() and, amplifier 42 'to the verticaldeflection electrode 44 (trfdeflecting coil circuitl` of Vtube 24.. As shown, it is applied to,V oneverticaldeection plate, one plate ofeach pair.-being.shown as grounded too'mpletethe dellecting circuit. Push-pull circuitry the dots areanexactisubl f rr'iay.r beathoughtfo-fasV afdevicefor passingonly ralternate pulses derived from sweep pulser 20. It follows that on alternate sweepspthe outputof adding crcuit '40C will beincreasedby the fixed height of; the pulse derived from voltage so that every other beat will' be displayed individer d6,` and-operates "to increase the vertical deflection dicated,V at..numeral.5 in a higher position uponftheA of. these events. will be evidenced by a lateral shift ofthe vertical center lines` of the two displays, as indicat'edilyiv smalll arrows on the tube face in Fig. 4, and the degree of deviation may easily be estimated'because` of the' df structure' of the two displays. Y

l lireq'uency'y varying system` The manner in which apparatus 14 operates-to provide ai small-'butrsubstantial changein theeifective frequency of., oscillator 1d will no'w be described in more'jdetail withl-ref'erence to Figs'. 2:' and 3. Referring rst to Fig'; 3the" normal sinefwave voltage output of oscillator 1.0

`islindicated at el, and this output is converted toa series Vso that infpoint of time the pulses e3 fall half-way` be tween successive pulses e2. In other words', series e3 is identical with e2 but shifted in phase by one-halfof the pulsel repetition interval; the pulses e2 maybe thought ofas` lining upfwith andproduced by the positive=ex`= cursions of e'land the pulses e3 line up with and are produced by thenegative excursions. of e1. As shown in Fig: 2, one set of pulsesV e2V is applied to aV first gate circuit 58', andthe other set of pulses is applied to a second! gate circuit 6i). GaterSS is to be thought ofV as normallyropen or conductive, so that pulses'eZ `areftransmittedj unchanged tof the frequency' divider 16. When gate: 58l isfclosed, however, asl by applying thereto-a negative square'pulse` ellV` of selected'length,l the Output of gate 58 will omitv al number of the pulsesV e2 deter mined by'therwidthi ofthe gating pulse e4'. As shown, this `gatingpulse is fed to gate S8 from a manualsel'ector switch62 which directs the gating pulse to gatenSS from thevariable width pulser 34 of Fig. l. When switchroz is thrown to its other position, the` variable widthpulsee4 willpass to a phase inverter 64 and thenceftofgate 6i), to open this latter gate (which is nor is preferablyV usedI in actu al` practiceYV as described-,hereinv after. The'` other input to addition circuit iisfderive'd from'isweep pulser 20, and may convenientlybe-afportion` .ofy the -p-ulse. energy furnished overv connection v32f-t0 th'evariable widthapulser' 34. This portion of' suchenergyisfappliedv to a frequency divider46 which-effects :1L-'frequency divisionby the. factor 2,2 and appliesythe resultingpulses toA th'eadding circuit ML--` When-there isznoyvvoltage outputfrom. divider. 46, .information from transducer 3S` atfectsthe vertical.4 deflection system.; of the`tube-24 to:produce on-its-l face a` display indicated for: creampie by numeralfld, and Vthe4 circuit .is :adjusted sen` thats thisa display .is noty centered.-y one the? sereen but 'of' series?l @3 Will be transmitted through gate" 60. and

u addedto (interspersed with the pulses of) the output of gate S8. The shapes of the-e4 pulse goingto gate SSvandLtheveS pulse gongto gateA 60 are shown inrFig. 3. ,.However, byother gating arrangements, gatesV 58 andtl may of course be operated in the manner dep scribed by other forms ofcontrolpulses. Thus, it would isa displaced fori` exampley to affvbelowlcenterposition'.

Simms-frequency, divid`er`46V has-a 'divisionfactor (of 2, -it

berobviousto omit phase inverter 64and designgate 60 so as to be opened by-a pulse of-ithe same polarity which closes gate 58. t f

With switch 62 inthe'position-shown, the arrival of an e4 pulse at gate 58- will eliminate or subtract'aY few passing; to divider l16, thisconditionl being indic'atedfin It has'been found that changing the effective frequency of output of oscillator 10 in this manner permits a frequency shift much greater than can be accomplished by any practical vernier 12. While it might be thought that the pulse trains e6 and e7 would be objectionable because of the fact that the pulses are abnormally crowded during a portion of each sweep, the fact that this action is followed by a substantial frequency division in divider 18 results in an output to sweep pulser 20 which is indistinguishable from a regular pulse cadence. No objection arises even as to the 330 pulseper-second output to the intensity electrode 28, because the frequency change is restricted to periods when display is not accomplished.

The length of gating pulses e4 and e5 is conveniently variable from zero to 1500 microseconds. In the embodiment shown, of course, a single control on the length of e4 is all that is required. At the scan rate of 5 beats per second, the total beat interval is 200,000 microseconds. This maximum e4 pulse length of 1500 microseconds thus permits up to 150 individual pulses to be gated out of the series e2, and up to 150 extra pulses of the e3 series to be inserted, because at 99 kc. each pulse period represents approximately 10 microseconds. An increment of one pulse added: or deleted represents about .00025 cycle per second change in the master frequency (in the case of beats per second), corresponding to about 41/3 seconds per day in the timepiece rate. It should be borne in mind that the only timing inaccuracy possible in this system assuming an adequate oscillator is an error in the width of the gating pulse e4 or e5. Since each step in the rate shift amounts. to about 4% second per day, 150 such steps represents a variation of about 650 seconds per day in each of the fast and slow directions, a'rate variation which is adequate to obtain stationary displays even for timepieces having gross rate errors. If the error in the width of pulse e4 and e5 is keptwithin 5%, the result would be at most an'uncertainty of about 33 seconds per day in the case-of estimating the maximum error of 650 seconds per day. Where the timepiece being measured is of greater accuracy than this, the uncertainty will decrease, and will of course become zero for the ideal condition, because no pulse e4 or e5 will then be required; i.e., the e4 pulse will be ofzero width.

- The adjustment for pulse width at the output of variable width pulser 34 is made by a calibrated dial, so that when a stationary display is obtained on tube 24, the dial setting indicates the timepiece error, and the position of switch 62 indicates whether it is fast or slow. When the watch is regulated nearly to perfection, rate errors of smaller magnitude than that corresponding to one step (addition or subtraction of a single pulse e3 or e2) may be estimated by the rate of drift of the display pattern across the tube face, in terms of the calibration dots making up the trace.

The chart in Fig. 4 gives typical values of the range of scan rates available with the above described'system for timepieces having beats of 5, 51/2`and 6 per second; it also yindicates the maximum error in a timepiece being inspected which can be measured using a maximum width of' 1500 microseconds for the pulses e4 and e5. These are convenient values for commercial purposes, but are of course not to be construed as limiting the invention to such gures.

Fig. 5 of the drawings is a detailed schematic of the embodiment described above, sufficient to enable one skilled in electronic circuitry to malte and use the invention.A Since the wiring details of the individual portions or components of this circuit are known in and of themselves or for other applications, actual circuit constants are considered unnecessary. Such details can be obtained from standard texts on circuit design. To enable the diagram to be followed, a general description of the purpose of each major part will now be given.

Description 0j circuitry In Fig. 5, ordinary direct current and voltage supplies for anode circuits, bias sources, cathode heaters and acceleration voltages (for the cathode ray tube) have been omitted for reasons of simplification. Typical sup ply voltage values are given, however. Also, numerals of reference for parts already mentioned above are employed to indicate those same parts in Fig. 3. Thus, nu'meral 10 designates the master oscillator employing crystal 66 as its frequency controlling element. The crystal frequency output is amplified as at 68 and the output (el of Fig. 3) is applied to the multivibrator 52 of adder/subtractor 14. Y

The open and closed gates are indicated by 58 and 60, each comprisinga pentode gate, the former controlled from manual switch 62 over lead 70 and the latter over lead 72. The frequency divider indicated as a whole by 16 may conveniently comprise a first stage 74 dividing by five, a second stage 76 dividing by ten, and a final stage 78 dividing by six to give a total divisor of 300. The divided output (nominal 330 pulses per second) appears on lead 80 and passes to the selective divider 18 comprising two stages. Stage 82 accomplishes division by eleven or twelve as selected by switch 84, and this switch is ganged to another switch 86 setting stage 88 to divide by six or ve. The switches are 3-position types connected as shown to give a net selection of division factor as among 66, 60 or 55 (6x11, 5x12 or 5x11). The output, of 5, 51/2 or 6 pulses per second, is applied to' sweep (and blanking) pulser 20 over lead 90, and lead 32 extends a portion thereof to variable-width pulser 34 controlling adder/subtractor 14. The Width of the pulse output from 34, which governs the number of pulses gated into or out of the el series of Fig. 3, is regulated by potentiometer 92, which therefore constitutes the rate adjustment of the instrument.

Sweep generator 22 is conventional and controlled by pulser 20, and controls the conventional horizontal detiection amplifier shown driving horizontal deliecton plates 26 (compare Fig. l). A portion of the output of sweep pulser 20 also passes via lead 30 to divider 46 (scale of two) to separate vertically the tick and tock traces. The same lead 30 proceeds through the manual brightness-control potentiometer 94 to the intensity control electrode 28 of cathode ray tube 24.

Microphone or vibration pickup 38 feeds a beat arnplilier96 supplying signal to vertical deflection amplifier 42 and thence to vertical deflection plates 44 (compare Fig. l). Conventional astigmatism and focus controls for tube' 24 are located at numerals 98 and 100.

A special feature of the circuit is in the use of a carrier system for blanking the trace of tube 24 between display intervals. Since the blanking rate is only of the order of five times per second, a heavily bypassed power supply would be needed to get satisfactory blankingv by direct application of blanking pulses on grid or cathode of tube 24. To avoid this, tube 102 is used as a blanking modu'- lator. It receives 99 kc. carrier energy from amplifier 52 over lead 104, and 330 cycle darkening pulses from tube 82 on its grid. Its plate voltage is positive only during the scan interval by virtue of the signal from pulser 20. The amplitude of this pulse is adjusted by the intensity control 94, and fed through resistor I106 to the plate of tube 102. Therefore, bursts of 99 kc. energy with S30-cycle holes appearv on the plate of tube 102, the bursts being the width of the blanking and sweep pulse of pulser 20. Such a frequency is readily coupled by capacitor 108 to a rectifier 110 where it is rectified Itdeniedtilated) rtto `-a id-cycle '-plilse which is @applied-'ibetweeirthe 'grid -28 #and 4:cathode of tube F24.

In order to maintain fthe pulser 34 locked to the fre- -fquency of oscillator y10, a little ofthe '99 -kcfoutputfrom vthe multivibrator '52 is 'fed over llead f-11'1'2fto' the Apulsers last stage. `This-prevents slight`wanderingofthepulser output.

`While the operation of sweep -gene'ratorf-ZZ -Iis "convenftionaL 'itis "stated that Vthe pulsereceived on its lgridfis negative,= milliseconds wide vand-recurs every 200milliseconds (ati cycles). Duringthe pulse, platecurrentin 22 ceases, and capacitor`114 charges -towards l300 volts. When -the pulse ends, plate f'current ow discharges-feapacitor H4 towards -l05 volts. The'voltageatthe-out- "-putlis'thus a sawtooth which returns to -itsbaseand stays 'ford/5 ofthe time, rising linearly during' the actual-sweep iinterval.

iFigu of the drawings showsthe yrelationship-of the Abeat *separation pulse from Idivider 46 (tolsepa'rate the 'tick and vtock -displays vertically from fone *another '.(lto the sweep voltage wave. The way in which :the .'sepvlar-ation -of/'successive ticka'nd tock vtra'ccsfoccurs'will be 'clear yfrornthis diagram.

While the description above-considers a'usual caserin which only the action at or'near `'the escapementtlp'eriod is displayed 4on scope 24, -cases 4may "arise rin 'which the entire f cycle -should be investigatedg'forexample, to ,detect conditions not arising 'from the escapement parts them# fselves., This'can'readily bedonelby'setting the ratecontro'l 92' to produce a 'fair'lyfrapid fdrift `of thetrace Aacross `the oscilloscope face; any 'portion rmay be :stopped for jinspection Vby resetting .the ratetc'ontrol for :'zero fdrift "when fa :desired part of thetrace is in view. The-.same `r'netliodpermits escapem'ent actionto be centered :rapidly on--tliescreen when 'a watch jislrstput under observation.

Alternate frequency varyingzsystem 'The system described above varies .the effective master oscillator pulse frequency by 'omitting `or adding various numbers of pulses.y An alternative 'approach will now be described.

Considering Fig. 5., fthe alteration in frequency is ob- Cil atained by adding or subtracting one or more pulses to or from the series developed-by multivibrator 52. Pig. l7

' illustrates a modication in which the gates for adding `or subtracting these pulses are omitted, and insteadthe frequency change is accomplished by momentarily valtering the scle or counting factor `of one of theffre'quency divider stages. The Vparts in "Figl `7 identical to those of 4the Afirst embodiment bearthe same legends and reference numerals asheretofore, and it will ,be noted that the pulse adder/subtractor is omitted. Assuming 'the oscillator 10rputs out pulses like ,the el series, or feeds a. multivibrator for producing such an output, vthe 99 kc. pulses are directed toa divider cha'inincluding a variable scale dividerZ and a following Xed scale divider 202, the divider 200 being settable todivide by (say) either -four or six under electronic control Afor a shortperiod, l

after which -it returns to the normal counting/rate or dividing ,scale of live as in the case of the rst divider `stage of element 16 in`Figs. l and l5. This can readily be :accomplished merely by alteringthe ring level of the tube in this 'first counter stage. 4When the scale of division is five, the Ve5 pulse from variable width pulser 34 would have to be long enough to cover the rst tiring from the starting point, the possible error being no greater than one pulse of the 99 kc. el series. The e5 pulse from pulser 34 would have to increase 50.5 microseconds in length for each additional 99 kc. pulse to be added or dropped; that is, this is the length of time that the scale of counter 200 would have to be altered from ve to four or from tive to six to change the average rate an amount corresponding toone 99 kc'. pulse per sweep cycle. lThus, for a changeV equivalent to 150 pulses of el, the e5 pulse would need to be 7.575 milliseconds tong. '.Ttiis e5 :pulsezshbuldzoacurlafterzeompletion of afrdisplay scan, 'ssinceizit r-'woutdrinterfere with up to live of the calibration "dotsi'if:itoccurredduring'the :display period.

OnewayMin :whichsuchean e5 pulse'could'lbe applied to thecontrol fof: the :counting scale'offdivider .1290.3is :illus- `trated :schematically-.1in Fi-g. :8. Comparing [this-diagram with fthe 'corresponding portion :near the beginningf of fthe counter'-stag'e 16 Aof Fig. 5, itwill:beseenlthat:thenegative voltage applied to the plate of the rsticountcr'niode i204 is --nowreceived through 'a resistor 206fformingthe `cathode Vresistor tof Va cathode follower `control 't tube 208. Since? the counting rate o1-:dividing factorfdepends-rupon the relationship between the voltage applied l:across l-lthe diodes-to Vthe capacitance ofrhe storage capacitor .210, ithe application `:of 'a -pulseifrom pulser 34 to the :grid -of'co'ntrol tube 238 will alter the counting yratefso-lo'ng-as the A'control fpulse lis applied, :and the direction :of alteration will :depend upon fthe 'polarity fo'fthe .control pulse. selection Tas between -slow "and fast-is obtained f-by *selecting the Apulse polarity :just fasin the-casemf :Figs 1 -and 5. .Theloutputpulsesonlead 212 are'carriedtothe '-usul blocking oscillator 214 associatedwith rthis .type ofstep-by-step counter.

Other ways in which Vthe counter scaleicould bewaltete'd "under control of :pulser 34wil1be 'apparent to `those faimiliarwith frequency `division circuitry. `Thus, the anr- Iplitude ofthe .pulses applied to the :first lcounter stage diode 204 Afrom 'oscillator v10` could :be-momentarily altered lornnodulated. bythe control-pulse from34, orfadditional capacitance could effectively be added to capacitor .-210orfsubtracted therefrom.

.While ithe zinvention fhas :been `described.inaccordance iwith vthe patent .statutes in lconnection with .a preferred embodiment-thereof, it is to .be understoodthatimoditi- -cations .may .be made byV those skilled .in the-art withott departing Yfrom the inventive principles. Also, while-the `apparatus has been described in connection `with-a watch `or timepiece -error measuring application, it will beiobvious that it may equally well `be `applied tothe measurement of any recurrent Vseries of events which can -be-exvpressed in terms kof a voltage' such-as the output voltage of .the-transducer or microphone 3S. .All such variations ifand modifications Aare considered a part of the -invention insofar Vas they fall i'within `the :scope-of Vthe appended claims.

What is claimed is: v

1. 4Precision timing apparatus formeasuring--and indicating the timerelationshipsamong time-spaced :recurrent events, comprising meansfor generating aser-ies of pulses -occurr-ingat a rate which islarge compared to therefcurrence Afrequency of said events,means..for:regulating l:the average ratefof-occurrence of said pulses through-at .least .one value which is -an integral multiple :of .saidarecurrence frequency, means fordividing the pulse sexies l'in .,frequencyto .provide a secondarypulse series having a .rate equal to the `.recurrence frequency of said events, rlmeans responsive `to the loutput `of `said dividing--means-for Venergizlng said regulating vmeans for -an interval uduring peach cycle of the output of said dividing means, adjust- -able control means for said responsive means-having indi- -cator means connected thereto to provide .an-indication `of the setting of said adjustable control means, .anoscilltloscope, .a time ibase-sweep .for- -said .oscilloscope connected for control by said dividing means, means for deecting the trace of said oscilloscope relative to its sweep axis in accordance Ywith the successive recurrent events, and trigger means controlled by said dividing means for energizing said time base sweep substantially only during the intervals of recurrence of said events, whereby the display on said oscilloscope is substantially coextensive in time with the periods occupied by said events to the exclusion of the time intervals therebetween.

A11 series, said indicator means being calibratedin terms of watch rate error to provide an indication of the number of pulses being interspersed or deleted.

3. Apparatus in accordance with claim 1, in which the means for regulating the recurrence rate of said pulses comprises a counter stage having an adjustable counting scale, said responsive means being responsive to the output of said dividing means for altering said counting scale for an interval during each cycle of the output of said dividing means.

4. Apparatus in accordance with claim l, in which said regulating means is energized by the output of said dividing means only during intervals between successive energization of said time base sweep.

5. Apparatus in accordince with claim 1, including a scale-of-two frequency divider connected to the output of said dividing means, and an axis-shift combining circuit connected to the output of said divider and to said trace-deecting means whereby to display successive of said events in separate positions on said oscilloscope.

6. Apparatus in accordance with claim l, including means for periodically suppressing the trace of said oscilloscope at a frequency which is a sub-multiple of the recurrence frequency of said series of pulses, to provide time markers in said trace.

7. Apparatus in accordance with claim l, including means for injecting a portion of the output of said means for generating the series of pulses into the circuit of said regulating means, whereby to stabilize the output phase of said regulating means with reference to said pulse series.

8. Apparatus in accordance with claim 2, in which said regulating means comprises means for deriving from said series of pulses a similar series delayed by one-half the pulse repetition interval, and a pair ofgates arranged for alternative operation respectively (a) to delete a selected number of pulses from the original series to reduce the average rate of recurrence thereof, and (b) to intersperse among the pulses of said original series a selected number ofthe delayed pulses to increase the average rate of recurrence thereof.

9. Apparatus in accordance with claim 7, wherein said responsive means comprises a variable width pulse generator, and means for applying the output of said variable width pulse generator selectively to either of said gates to achieve increase or decrease in the average recurrence rate of the original puls'e series.

10. Apparatus in accordance with claim 8, wherein said indicator means comprises manually adjustable means calibrated in terms of watch rate error for varying the width of the pulse produced by said variable width pulse generator, and including manually settable means for said regulating means calibrated in terms of slow and fast watch rate errors for applying the variable width pulse to the selected one of said gates.

11. Precision timing apparatus for measuring and indicating the time relationships among time-spaced recurrent events, comprising means for generating a series of pulses occurring at a rate which is large compared to the recurrence frequency of said events, means for regulating the average rate of occurrence of said pulses through at least one value which is an integral multiple of said recurrence frequency, means for dividing the pulse series in frequency to provide a secondary pulse series having a rate equal to the recurrence frequency of said events, means responsive to the output of said dividing means for energizing said regulating means for an interval during each cycle of the output of said dividing means, adjustable control means for said responsive Ameans having indicator means connected thereto to provide an indication of the setting of said adjustable con- Vtrol means, an oscilloscope, a time base sweep for said oscilloscope connected for control by said dividing means, means for deflecting the trace of said oscilloscope relative to its sweep axis in accordance with the successive recurrent events, trigger means controlled by said dividing means for energizing said time base sweep substantially only during the intervals of recurrence of said events, whereby the display on said oscilloscope is substantially coextensive in time with the periods occupied by said events to the exclusion of the time intervals therebetween, and means for selectively altering the division ratio of said dividing means to accommodate gross differences in the recurrence interval of said recurrent events.

12. In a timepiece testing and timing device of the type having an oscilloscope indicator, a precision frequency source, a transducer for converting beats of said timepieceinto an electrical signal, and circuits for applying voltages from said source and said transducer to respective deecting means in said oscilloscope for displaying the beats of said timepiece against a calibrated time scale defined by said source, the improvement which comprises: selective means for altering the effective output frequency of said source in discrete steps to synchronize with ,the nominal beat frequencies of different timepieces, means for generating a square wave in synchronism with the effective output of said source and having a half wave period equal to the beat interval of the timepiece being tested, and adding means for combining the output of said generating means with the velectrical signals from said transducer to apply the sum thereof to the oscilloscope deecting means adapted to receive voltages from said transducer, whereby the displays for alternate beats of the timepiece are separated on the screen of said oscilloscope.

13. A device in accordance with claim 12, in which the frequency of said precision source is a multiple of the least common multiple of the frequencies corresponding to the discrete steps selectable by said selec'- tive means.

14. A device in accordance with claim 12, and including additional means for varying the effective output frequency of said precision source substantially continuously over a range of values less than the separation of said discrete steps.

References Cited in the file of this patent UNITED STATES PATENTS 2,121,359 Luck et al. Jan. 21, 1938 2,285,038 Loughlin .Tune 2, 1942 2,317,202 Kohlhagen Apr. 20, 1943 2,535,304 Lindborg Dec. 26, 1950 2,648,027 Geohegan Aug. 4, 1953 2,677,783 Wilson May 4, y1954 2,760,108 Wilson et al. Aug. 21, 1956 

